I was told when we adopted our dog that you should have a crate in an easily accessible, comfortable place so your pup can associate it as their safety “den” or “cave.” The door should be always open while you are home so they can go in and out as they please. Always praise him/her when they go in on their own and reward with treats. Keep items that your dog associates as “security items” within the crate such as a blanket or a teddy bear. Once it is time to go and you must shut the crate door, continue to praise the dog and reassure him/her that you’ll be back. Then I find it helps to turn on the radio or music in your absence. If you live in a quiet house without a lot of people, classical music is soothing. Or if your dog is used to a lot of talk/noise in the house, talk-radio is helpful. Also there are “doggie entertainment” videos which play on “loop” for them to watch if he/she has an interest in TV. This will help them realize that crate-time is just down-time.